Tool changers provide metal cutting machine tools with the ability to store and automatically select from a plurality of cutting tools. This allows a single machine tool to perform a series of different machining operations without having to manually change tools. Over time, however, the tools become dull or worn to the point where they must be sharpened or replaced.
In a stand-alone machine tool, referred to herein as a CNC machine tool, the interchangeable tools are stored in a tool magazine positioned overhead or alongside a work zone where machining takes place. It is known for such a tool magazine to be supported for reciprocal motion between a stowed tool position clear of the spindle to be serviced, and a tool change position within the reach of spindle for tool exchange. When the tools in the magazine need to be sharpened or have worn out, it is relatively easy for an operator to move around and gain access to the magazine of a stand-alone CNC machine tool to remove and replenish the tools.
In a transfer line, however, machine tools generally do not stand alone, and access is very limited. A series of machines called transfer machine modules, referred to here as TMMs, are arranged close together in a series along a dedicated transfer mechanism. The transfer mechanism transfers workpieces through an area called a work zone tunnel where the various TMMs are able to perform machining operations on them. Because the work zone tunnel must be free of obstructions, the tool changer cannot occupy this space. Accordingly, it is known to position a tool magazine above each of the TMMs. The tool magazines are positioned above the forward ends of the modules, adjacent to the spindles, and adjacent to the work zone tunnel. The close proximity of adjacent TMMs and the need to keep the work zone tunnel free of obstructions creates a problem for personnel who must carry heavy tools to and from the tool magazines for tool replenishment. In some cases, an operator must move a rolling step ladder, as close as possible to the magazine, then climb the ladder with replacement tools, and reach out two or three feet toward the work zone tunnel to remove and replace the tools. The operator then must carry the spent tools down the ladder, and in many cases roll the ladder away from the transfer line. As the tools are relatively heavy, this is not an ergonomically friendly operation. In addition, a rolling step ladder unit of sufficient stability takes up a significant amount of valuable floor space. Since it is not uncommon to have lubrication and cutting fluids on the floor in the vicinity of the TMMs, the floor is slippery, and the fluids get transferred to the steps of the ladder by the worker's shoes, making the tool replacement process even more precarious. This particular problem exists both for TMMs and CNC machine tools.